The present invention is directed to valvulotomes useful in medical procedures for removing valves from veins.
Techniques have been developed to reduce the invasiveness of bypass surgery to treat peripheral vascular disease blocking a patient's artery. Traditionally, a large incision is made in the patient's leg through which either a synthetic graft or a vein of the patient taken from another place in the body is inserted to bypass a diseased section of artery. A minimally invasive alternative is to use one of the patient's veins in place, or in situ, for the bypass. However, in order for this procedure to be effective, the valves of the vein ("venous" valves), which normally prevent reverse blood flow, must be removed. Angioscopy, i.e., the visual observation of the interior of a blood vessel by use of an endoscope inserted into the vessel, is preferably used by the surgeon during the valve removal procedure to optimize its efficacy and minimize vein damage.
The use of valvulotomes for cutting or disrupting vein valves, is discussed in the prior art. For example, only see:
______________________________________ Segalowitz U.S. Pat. No. 5,092,872 Nobles U.S. Pat. No. 5,026,383 Chin U.S. Pat. No. 4,739,760 Leather U.S. Pat. No. 4,493,321 ______________________________________
In a typical valve removal procedure, a first end of a pulling catheter is inserted through a distal vein incision and advanced through the vein until it exits from a proximal vein incision. Because normal blood flow through the vein is in a distal to proximal direction, the pulling catheter moves past the valves by simply pushing the valve leaflets aside in their natural direction of motion.
At the site of the proximal vein incision, the pulling catheter first end is attached to a valvulotome distal end. The pulling catheter is then pulled back through the vein enabling cutting edges on the valvulotome to cut the valve leaflets. Progress of the valvulotome through the vein can be monitored on a viewing scope near the proximal end of the valvulotome which displays an image captured at the valvulotome distal end.
In order to minimize vein wall damage, it is preferable to configure the valvulotome to prevent contact between the cutting edge and vein wall while the valvulotome is advancing through the vein. It is also desirable to maximize the field of view available in the imaging window at the valvulotome distal end.